BL 8 inch Mk VIII naval gun
|origin= United Kingdom |type= Naval gun Coast defence gun |is_ranged=YES |is_bladed= |is_explosive= |is_artillery=YES |is_vehicle= |is_UK=YES |service=1927 - 1954Whitley 1995 pp.17,83&89 |used_by= |wars=Second World War |designer= |design_date= |manufacturer= |production_date= |number=168Campbell 1985 pp.31-33 |unit_cost= |variants= |weight=17.5 tonnes |length= |part_length=400 inches (10 meters) |width= |height= |crew= |cartridge= |caliber= |action= |rate= |velocity=2805 feet per second (855 m/s) |range= |max_range= |feed= |sights= |breech= |recoil= |carriage= |elevation= |traverse= }} The 50 calibre 'BL 8 inch gun Mark VIII'Mark VIII = Mark 8. Britain used Roman numerals to denote Marks (models) of ordnance until after World War II. Hence this was the eighth model of BL 8-inch naval gun. was the main battery gun used on the Royal Navy's County-class heavy cruisers,A more accurate term is "Treaty Cruiser", as the term heavy cruiser was only formally defined at the time of the London Naval Treaty of 1930. However, all the 8-inch gun cruisers introduced as a result of the 1922 Washington Treaty were what became known as "heavy cruisers". in compliance with the Washington Naval Treaty of 1922. This treaty allowed ships of not more than 10,000 tons standard displacement and with guns no larger than 8 inches to be excluded from total tonnage limitations on a nation's capital ships. The 10,000 ton limit was a major factor in design decisions such as turrets and gun mountings. A similar gun formed the main battery of Spanish ''Canarias''-class cruisers.Campbell 1985 p.389 In 1930, the Royal Navy adopted the BL 6 inch Mk XXIII naval gun as the standard cruiser main battery in preference to this 8-inch gun.Whitley 1995 pp.96-127 Description These built-up guns consisted of a wire-wound tube encased within a second tube and jacket with a Welin breech block and hydraulic or hand-operated Asbury mechanism. Two cloth bags each containing 15 kg (33 pounds) of cordite were used to fire a 116-kg (256-pound) projectile. Mark I turrets allowed gun elevation to 70 degrees to fire high-explosive shells against aircraft. Hydraulic pumps proved incapable of providing sufficient train and elevation speed to follow contemporary aircraft; so simplified Mark II turrets with a maximum elevation of 50 degrees were installed in the Norfolk subgroup ships and and the ''York''-class cruisers and . Each gun could fire approximately five rounds per minute. Useful life expectancy was 550 effective full charges (EFC) per barrel. Naval service The following ships mounted Mk VIII guns in 188-tonne twin turrets. The standard main battery was four turrets, but Exeter and York carried only three to reduce weight and formed the separate ''York'' class.Lenton & Colledge 1968 pp.36-39 *County-class heavy cruisers : 14 ships *''York''-class heavy cruisers : 2 ships Coast defence guns Six single guns capable of elevating to 70 degrees were installed as coastal artillery in the Folkestone-Dover area during the Second World War. Ammunition File:BL8inchSAPKMkIBNTShell1943Diagram.jpg| World War II semi-armour piercing shell with marker dye to identify ship that fired it for range corrections File:BL8inchHENavalShellDiagram1934.jpg| 1930s high explosive shell File:428 Battery setting 8 inch shell fuzes WWII IWM TR 564.jpg| Coast-defence gun shells, World War II Shell trajectory Weapons of comparable role, performance and era *203mm/50 Modèle 1924 gun French equivalent *20.3 cm SK C/34 Naval gun German equivalent *203 mm /53 Italian naval gun Italian equivalent *20 cm/50 3rd Year Type naval gun Japanese equivalent *8"/55 caliber gun US equivalent Surviving examples * A gun from HMAS Australia outside the Australian War Memorial, Canberra Notes References * * * External links * Tony DiGiulian, Britain 8"/50 (20.3 cm) Mark VIII Category:Naval guns of the United Kingdom Category:Coastal artillery Category:203 mm artillery Category:World War II naval weapons of the United Kingdom